Method for air moistening

ABSTRACT

Method of humidifying a cold air stream in which movable surfaces of low heat conductivity mounted in a housing of low heat conductivity are continuously wet by a thin cohesive film of water obtained by dipping the moving surfaces in a water bath maintained in constant level at a constant temperature above the temperature of the air then the wet moving surfaces being exposed to the air stream to be humidified.

United States Patent 1 Tamm Mar. 26, 1974 METHOD FOR AIR MOISTENING [76] Inventor: Walther Johann Tamm,

' Georgenstrasse 38 B.R.D., Munich,

, Germany [22] Filed: Mar. 12, 1971 [21] Appl. No.: 123,747

[30] Foreign Application Priority Data Mar. 14, 1970 Germany 2012373 56] References Cited UNITED STATES PATENTS 1,786,200 l2/1930 Ferguson 261/92 X 1,824,891 9/1931 Hill 261/92 X 1,827,828 10/1931 Spalding 261/92 X 1,844,942 2/1932 Buttfield 261/142 UX 1,986,873 1/1935 Yoch 261/D1G. 34 2,001,410 5/1935 Cook 261/92 X 2,066,832 1/1937 Gay 261/116 X 2,144,626 1/1939 Hewitt 261/141 X 2,678,810 5/1954 Chandler 261/92 2,703,228 3/1955 Fleisher 1 261/130 X 3,149,626 9/1964 Wentling et a1. 261/92 X 3,177,126 4/1965 Charresu 261/92 UX 3,193,259 7/1965 Liebmann...-. 261/DlG, 15 3,211,148 10/1965 Galajda, Jr 261/142 X 3,358,739 12/1962 Pinkerton et a1. 261/92 UX 1,922,147 8/1933 Wales 261/26 X 2,858,621 11/1958 McMillan 261/92 X OTHER PUBLICATIONS Arrow Louvers & Dampers, Arrow Louver and Damper Corp., 41 Box St., Brooklyn 22, N.Y., page 12 relied on, received 6p 180, Sept. 24, 1965.

Primary Examiner-Tim R. Miles Attorney, Agent, or Firm-Sol B. Wiczer 57 ABSTRACT Method of humidifying a cold air stream in which movable surfaces of low heat conductivity mounted in a housing of low heat conductivity are continuously wet by a thin cohesive film of water obtained by dipping the moving surfaces in a water bath maintained in constant level at a constant temperature above the temperature of the air then the wet moving surfaces being exposed to the air stream to be humidified.

8 Claims, 3 Drawing Figures 1 METHQD FOR AIR MOISTENING ous wetting of the heating surfaces. For reasons of safety, moreover, a water overflow must be provided to 'carry off the excess water which is not evaporated when heated. This necessitates the installation of a pipe to carry the excess water to a box drain. This imposes a considerable limitation on the use of this method, since a drain of this kind is not always available or located a short distance away. If there is too much water overflow, correspondingly high heat losses will result; and if there is too little water, the spray nozzles will be blocked or the water supply will stop completely so that the air flowing over the surfaces will be heated instead of moistened. In moistening the air in refrigerator and freezer rooms, which can accept only low humidity levels, the vapor must be supplied with interruptions, during which it can spread out over the entire room. It is necessary to prevent considerable fluctuations of the relative humidity, and this requires a complicated switching apparatus.

The object of the invention is a method for moistening air which .does not have these shortcomings. The water surface is created as follows: discs mounted on a rotating axle with one segment submerged in a. water bath, are set to rotating, so that the water which adheres to the segmentsspreads over the entire surface of the discs in a thin cohesive film. According to the in vention, the water is heated, but not the discs. The latter, therefore, do not need to conduct heat, but are made instead from a material with the lowest possible thermal conductivity, so that when the discs are stopped, the amount of heat given off from the discs to the room air passing over them is as small as possible.

The following is a description of the embodiment of the invention as shown in thedrawing. In the drawing:

FIG. 1 is a side view of the device for accomplishing the method according to this invention;

FIG. 2 is a front view of the apparatus according to FIG. 1; and

FIG. 3 is a top view of the apparatus according to FIG. 1.

The figure shows a device embodying the invention. In this figure, 1 is a base plate on which the bottom of a housing 2 and supports for a gear drive 3 and a drive motor 4 are fastened with a watertight seal. Housing 2 is made with double walls, with the space between them filled with a heat-insulating material 5. Two opposite sides of the rectangular housing 2 have recesses provided to accept bearings 6. The latter support an axle 7, on which circular plates 8 are mounted at intervals, each having a segment submerged in water bath 9, which isheated by heater l and whose temperature is kept constant by a thermostat 11. A float valve 12 in the feed water line 13 maintains the water level in the bath 9 at a constant level. One of the other two sides of the housing 2 is provided with a fan 14 and the opposite side contains an automatically closing shutter l5.

Fan 14 and shutter 15 are installed after the upper part of housing 2 has been installed and bolted to the lower part. A device 16 consisting of sloping slats, fastened to the lower part, serves to deflect drops of water thrown off by the rotating plates. Axle 7, which protrudes from housing 2, is connected by a flexible coupling 17 to gear drive 3, and the latter is connected to drive motor 4 by flexible coupling 18.

The device works as follows:

Water bath 9 is kept at a thermostatically adjustable temperature of approximately 25 to 40 C, even during interruptions in operation. When a moisture regulator located in the room (not shown) calls for supplying moisture to the room air, drive motor 4 and fan 14 are switched on simultaneously. This starts the plates 8 to rotating, so that new plate elements are continuously submerged in water bath 9 and the water which adheres to them spreads out over the entire surface of the plates. The warm water then evaporates in the air which is drawn in from the room by fan 14 and blown over the rotating plates 8 out through the automatically opening shutter 15, enriched with water vapor, back into the room. Any drops of water which may be thrown off from the plates strike the sloping surfaces of the deflector 16 and run back into the water bath. When the room air has reached the upper limit of relative humidity set by the moisture regulator, the latter switches off drive motor 4 and fan. 14, and the shutter closes automatically. If rooms with low temperatures make it necessary to supply moisture to the air at intervals, a timer (not shown) is connected to the power line which runs to drive motor 4 and fan 14 and is used to control the duration of successive periods of operation and inoperation. Since only a thin water film forms on plates 8, which evaporates very rapidly, the supply of moisture to the room air stops immediately when the plates stop moving and begins immediately when they start to turn again. The surface of water bath 9 is very small when compared to plates 8, so that the amount of water vapor formed above it during the pauses in operation is comparatively small and is also kept from mixing with the room air by means of shutter 15. Housing 2 is insulated in order to keep the heat loss from its walls to the room air as small as possible; this becomes increasingly necessary with decreasing room temperature. For the same reason, it should preferably be made of plastic material which conducts heat poorly. Plates 8 rotate at approximately to 200 rpm. This requires the use of a gear drive 3 to reduce the rpm of drive motor 4 to that of the plates. The drive needs to overcome only very low torque, since only the frictional re sistance of the plate segments in the water must be overcome. A friction wheel drive could be used for the same purpose. A conventional small electric motor is used as drive motor 4.

The method has greater operational safety in comparison to those known previously, as well as greater economy of operation, a wider range of application, longer service life and lower manufacturing costs. It uses no nozzles or water valve systems which could easily be blocked. The possibility of a failure in producing a continuous film of water is practically excluded, nor is it possible that the air could be heated instead of moistened, as often happens with other methods.

Because no water overflow need be provided to insure wetting, there are no heat losses due to overflow of water which is heated but not used. Since the carrier surfaces for the water film are not heated, no deposits from the water form on them which could in time cause deterioration of heat transmission.

The method is suitable for moistening air down to any'temperature. It uses no nozzles or water valve systems which could freeze and makes it very simple to supply moisture at intervals in adjustable small amounts. Air moistening devices of this kind may be located anywhere in the room, since there is no water overflow line which must be connected to a box drain.

Devices operating according to this method have a very long lifetime. There are no deposits from the water on the heating surfaces which would make it necessary to replace them after a certain period of operation. The carrier surfaces for the water film are not subjected to wear or corrosion, temperature or heat stresses; their lifetime is practically unlimited. With the low rotational speeds and the low torque which must be overcome, approximately the same may be said of the other moving parts of the device operating according to the method. Only the electrical heating rods have a limited lifetime, and they can be replaced easily and are readily available.

Since devices operating according to the method offer large evaporating surfaces on a small base, they have comparatively small dimensions. The cost of the carrier surfaces for the water film, made of thin plastic plates, is only a fraction of that for carrier surfaces which serve simultaneously as heating surfaces. For these reasons, it may be expected that installations which operate according to this method can be manufactured at comparatively low cost.

I claim;

1. Method of humidifyin g air by evaporation of water from water-wet surfaces of a self-contained humidifier unit, said unit being readily movable to any selected place in the space to be humidified, and having its inlet and outlet in direct communication with said space, comprising passing the air to be moistened over said water-wet surfaces which are imperforate, comprising rotating discs, said discs having segments immersed in a heated water bath heated to a constant thermostatically controlled even temperature above the temperature of the air in said space whereby to wet and coat each total disc surface with a thin cohesive film of heated water at the raised temperature of the bath as the disc rotates.

2. Method according to claim 1 wherein said humidifier is portable and the plurality of plates are mounted for rotation upon a rotatable shaft disposed at right angles to two opposite sides of a housing with a lower portion of said plates dipping into a heated water bath, and a fan is provided in the third side serving to draw air into said housing from the space to be humidified and blow it over the rotating wet plates out through an automatically closing shutter and back into the room.

3. The method as defined in claim 1 wherein said water bath is maintained at a substantially constant level.

4. The method as defined in claim 1 wherein said discs are slowly rotated mechanically at a slow, substantially constant speed with a segment of each disc dipping into said bath.

5. The method as defined in claim 1 wherein said discs are formed of relatively poor heat conductive substances.

6. The method as defined in claim 1 wherein the humidification is applied to the air to be humidified intermittently at timed intervals.

7. The method as defined in claim 1 wherein said rotating discs are mounted for rotation in a housing having poor heat conductivity, and the air to be humidified is passed through said housing in contact with said wet disc.

8. The method as defined in claim 7 wherein said housing is heat insulated. 

1. Method of humidifying air by evaporation of water from waterwet surfaces of a self-contained humidifier unit, said unit being readily movable to any selected place in the space to be humidified, and having its inlet and outlet in direct communication with said space, comprising passing the air to be moistened over said water-wet surfaces which are imperforate, comprising rotating discs, said discs having segments immersed in a heated water bath heated to a constant thermostatically controlled even temperature above the temperature of the air in said space whereby to wet and coat each total disc surface with a thin cohesive film of heated water at the raised temperature of the bath as the disc rotates.
 2. Method according to claim 1 wherein said humidifier is portable and the plurality of plates are mounted for rotation upon a rotatable shaft disposed at right angles to two opposite sides of a housing with a lower portion of said plates dipping into a heated water bath, and a fan is provided in the third side serving to draw air into said housing from the space to be humidified and blow it over the rotating wet plates out through an automatically closing shutter and back into the room.
 3. The method as defined in claim 1 wherein said water bath is maintained at a substantially constant level.
 4. The method as defined in claim 1 wherein said discs are slowly rotated mechanically at a slow, substantially constant speed with a segment of each disc dipping into said bath.
 5. The method as defined in claim 1 wherein said discs are formed of relatively poor heat conductive substances.
 6. The method as defined in claim 1 wherein the humidificatIon is applied to the air to be humidified intermittently at timed intervals.
 7. The method as defined in claim 1 wherein said rotating discs are mounted for rotation in a housing having poor heat conductivity, and the air to be humidified is passed through said housing in contact with said wet disc.
 8. The method as defined in claim 7 wherein said housing is heat insulated. 